Arc lamp mechanism



Jan. 20, 1942. c. T. cR'ocKER ARC LAMP MECHANISM Filed De..

22', 1939 2 Sheets-Sheet l Inventor: "C Iarence T' Cracker;

His Attortney Jan.20,l942; '.T.cRocKER ARC LAMP MECHANISM Filed Dec. 22, 1939 2 Sheets-Sheet 2 Inventor Clarence "I". Cr'ocker;

ans Att OTneB.

Patented Jan. 20, 1942 ARC LAIVIP MECHANISM Clarence T. Crocker, Daytona Beach, Fla., assignor to General Electric Company, a corporation of New York Application December 22, 1939, Serial No. 310,597

7 Claims.

My invention relates to arc lamp mechanisms, and more particularly to electrode feeding mechanisms for high powered arc lamps such as are applicable for searchlight use.

One object of my invention is the provision of an improved mechanism'for feeding an electrode at rates variable in proportion to the fluctuations in predetermined arc characteristics.

Another object of my invention is to minimize the mechanical load on the regulating magnet of an electrode feeding mechanism to increase its sensitivity.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the accompanying drawings, Fig. 1 is a side elevation, partly diagrammatic, of a conventional ar-c lamp mechanism provided with a control mechanism built in accordance with my invention; Fig. 2 is a perspective view of the control mechanism of Fig. 1 including all its control elements with the interconnecting shafts elongated so that each element may be viewed in its relation to the other elements of the mechanism; Fig. 3 is an enlarged perspective view of a group of elements illustrated in Fig. 2; and Fig. 4 is an enlarged side view of a part of the mechanism illustrated in Fig. 3.

Referring to the drawings in detail, Fig. 1 i1- lustrates, diagrammatically, a conventional electrode feeding mechanism for feeding both of the electrodes of an arc lamp, automatically or manually, independently of each other. The negative electrode Ill is supported on two pairs of rollers ||--l| and |2I2', of which rollers |2-|2 are actuated to feed the electrode. These rollers are mounted on shafts |3-|3, respectively, having interengaging gears l4 and I4 mounted on their ends. These gears are in turn driven by a worm l5, engaging the gear l4, and mounted on a shaft 16. Shaft I6 is driven through beveled gears I1 and I1, the latter of which two gears is mounted on a shaft H3. The mechanism for driving shaft I8 is mounted in a box I9 and is shown in detail in Figs. 2, 3, and 4.

Still referring to Fig. 1, a positive electrode is supported, for rotation about its own axis and for axial movement, within a cage 2 I. This cage 2| is a U-shaped member supported at its closed end by a hollow shaft 22 which is coaxial with the positive carbon. This cage and shaft are rotated by a mechanism including a bevel gear 23 mounted on the end of the shaft 22, a bevel gear 24, mounted on a shaft 25, bevel gears 26 and 26' and a shaft 21. The mechanism for driving the shaft 21 is enclosed in the box I9 and is shown in detail in Figs. 2, 3, and 4.

The positive electrode 20, as illustrated in Fig. 1, is supported within the cage 2| by a pair of feed rollers 3|l30' which are rotated to axially advance, or feed, the carbon. The feed rollers are mounted on shafts 3| and 32, respectively. The shafts 3| and 32 are supported in the sides of the cage 2| and are connected by interengaging gears 33 and 34 mounted on the shafts. They are driven by a system of gears including a gear 35 mounted on the shaft 3|, a gear 36 engaging gear 35 and mounted on a shaft 31, a gear 38 also mounted on the shaft 31, and by a worm 39 which engages gear 38. The worm 39 is mounted on a shaft 40 projecting through the end wall of the cage 2|, upon the other end of which a gear 4| is mounted. Gear 4| engages a gear 42 which is rotatable on the hollow shaft 22 and is connected by pins 43 to a cam 44. When the shaft 22 is rotated, the cage 2| and the described system of shafts and gears move with it, and no axial movement of the positive electrode 20 takes place. If, however, during the movement of shaft 22 the cam 44 is held stationary, the gear 42 remains stationary and gear 4| rolls about the axis of gear 42. The entire train of gears between the cam 44 and the feed rollers 303|| is thereby set into motion and a forward movement of the electrode 20 takes place.

For the purpose of holding the cam 44 stationary, the cam 44 is built in the form of a ratchet wheel, and a pawl 45 i mounted on a shaft 46 for cooperation with this wheel. Normally this pawl is held in a position parallel to the cam 44. When it is desired to hold the cam 44 stationary, this pawl 45 is moved about the axis of the shaft 46 over an arc of into the path of movement of the ratchet teeth. The cam moves until the face of a tooth engages the pawl 45, and then remains stationary as long as th pawl is held in this second position. The pawl shaft 46 is moved by bevel gears 4|4l' and a shaft 48. The mechanism for moving the shaft 48 is also enclosed in the box |9.

At the side of the box 9, two cranks 50 and 5| are shown. These are provided for the manual operation of th shafts l8 and 21, respectively. A knob 52 is provided and positioned between the two crank for adjusting the linkage mechanism which actuates the shaft 48 and the pawl 45.

Fig. '2 illustrates in an expanded perspective view the operating mechanism enclosed in the box I9 of Fig. l. The shafts interconnecting the respective gears are elongated for the purpose of more clearly illustrating the interconnection between the gears and the other elements which perform the several functions of the mechanism. The prime mover for the mechanism i a motor 53. This motor drives the shaft 2'! of the positive electrode rotating mechanism, through a worm 54, interengaging gear 55, shaft 56, gears 5'I5B, shaft 59, and bevel gears 60-60' of which gear Gil is mounted on the shaft TI.

The shaft 21, as above stated, may also be rotated manually by the crank 5|. This crank is mounted upon a shaft upon which one jaw 62 of a coupling is mounted. The second jaw 63 of this coupling is mounted on a shaft 64 1111011 is connected to the shaft 21 through bevel bears -05. The jaws 62-53 of the coupling are normally held in disengaged position by a spring 06. The crank 5| and shaft BI may be moved axially against the pressure of this spring to bring into engagement the two jaws Iii-63 of the coupling. The coupling will transmit torque only in one direction; that is, in the direction of normal rotation of the electrode, and in this direction the shaft 21 may be moved ahead of the movement imparted by the motor 53. For this purpose, a ball clutch is provided between the gear 58 and the shaft 59. This is merely a standard form of ball clutch in which balls ill roll into notches in the hub 68 of the gear 58 to release the shaft and permit relative movement between the shaft 59 and the gear 58 when the shaft 59 is moved ahead of the gear. When the gear 50 is first rotated, however, a slight movement between the gear and shaft 59 causes the balls 61 to wedge between the shaft 59 and the gear hub 68, and the shaft is thereafter rotated with the gear.

The feeding mechanism for the positive electrode may be actuated automatically at regular intervals, manually at any desired interval, and automatically in response to a condition of the electrode, such as, for example, a change in the length thereof and the resulting change in the position of the electrode tip. The regular intermittent movement is imparted thereto by an actuation of the pawl 45 through a cam H mounted on the shaft 21 and a cooperating actuating mechanism. This actuating mechanism for the pawl 45 includes a roller 12 mounted on a lever 13 which is pivoted between its ends upon a pin I4. The lever I3 actuates a link shaft I5 upon which an adjustable nut 16 is mounted and connected to a lever IT. The lever I? is pivoted near its center upon a pin I8, and through a pin connection I9 is connected to a link 80. The link 80 is connected to one end of a crank 8| which is mounted upon the shaft 48 (see Fig. l). A rotation of the cam II effects a rotation of the shaft 48 through the mechanism just described to cause the pawl 45 to move into the path of the cam 43 once during each revolution of the shaft 21.

An additional movement of the electrode may be superposed by the manual rotation of the crank M, which by rotation of the shaft 21 increases the speed of rotation of the cage -2I, and simultaneously increases the frequency of operation of th pawl 45 to effect a greater speed of forward movement of the electrode 20.

The knob 52, mounted on the side of the control box, is operable to adjust the linkage between the cam II and the shaft 48. The knob 52 is mounted upon a shaft 82, and is connected to the threaded shaft 15 through a sleeve 03, mounted on the shaft 82, and a pin 84 mounted on the shaft I5. The sleeve is provided with slots 85 to receive the pin 84 and thereby form a pin and slot connection between these two shafts. The lever 13 is connected to the shaft I5 by engaging the sides of a nut 85, the lever I3 being bifurcated at its end for this purpose. The ends of the lever 13 are held in a channel formed by flanges 81 projecting from one side of the nut and engaging one side of the lever ends, and a plate 80 loosely mounted on the shaft I5 engaging the other side of the nut and of the lever ends. The plate 88 is held against the lever ends by a spring 89 which is under compression between the nut 10 and the plate 08. A turning movement of the knob 52 rotates the shaft I5 and opposite threads on the shaft regulate the distance between the nuts 86 and I6 and thereby adjust the linkage mechanism.

The pawl shaft 48 may also be moved by the encrgization of a magnet 90 which attracts its armature 9I, pivoted upon pin 92. The armature is connected to the shaft 48 through a linkage mechanism including link 93, lever 94 pivoted near its center on pin 95 and connected to the shaft 00 by a pin 96 and slots 91 in the end of the bifurcated end of the lever 94. The circuits for energizing the magnet 90 are not illustrated in this diagram. There are now many devices in use for feeding the positive electrode to maintain its tip in a predetermined position, one such device being described in United States Patent 1,313,666, issued August 19, 1919, to Beck. The magnet 90 may be energized in response to any one of such devices.

It is necessary to move the negative electrode axially to strike the arc and also to regulate the intensity of the arc during operation. It is desirable, therefore, to provide a mechanism which is sensitive to a condition of the arc and which will effect a movement of the electrode to establish and maintain this desired condition of the arc.

The mechanism, built in accordance with my invention, for feeding the negative electrode, as illustrated in Fig. 2, includes the motor 53, worm 54, gear 55, and the shaft 56 of the positive electrode mechanism. To drive the negative electrode mechanism, a gear I00 is mounted on the shaft 56. This gear I00 engages a gear IOI mounted on a shaft I02. The shaft I02 carries two gears I03 and I04 which are loosely mounted thereon and are alternately connected to the shaft by a pawl and ratchet mechanism actuated in response to an are characteristic or condition, such as, for example, the voltage across the are or the current through the arc. The gear I03 engages a gear I05 on a shaft I06 and drives this latter shaft in a clockwise direction when connected to the shaft I02. The gear I04 engages a pinion I01 which in turn engages a gear I08 also mounted on the shaft I06, and thereby drives the shaft I06 in a counter-clockwise direction when it is connected to the shaft I02. The gear I09 mounted on the end of the shaft I05 drives the negative electrode feeding shaft I8 (see Fig. 1.) through a gear IIO mounted on a shaft III and by a pair of bevel gears H2 and H2, the first of which is mounted on the shaft III, and the second of which is mounted upon the shaft I8.

This shaft I8 may also be driven,

manually, by the crank 50. This crank 50 is mounted upon to receive the prongs H9 and I20.

a. shaft H3 rotatably mounted in a disk H4. The disk I I4 is spaced from the gear I I by rods H5 and II 6. The gear H0 is slidably mounted upon the shaft H I and is normally held in position to engage the gear I09, by a spring II1. When it is desired to operate the shaft I8 manually, the crank 50 with shaft H3 and disk H4 is moved axially of the shaft II I, the shaft H3 being provided for this purpose with a sleeve H8 which slides over the end of the shaft III. This movement disengages the gear H0 from the gear I09 and places prongs H9 and I20, attached to th disk I I4, in engagement with a disk I2I. This disk I2I is rigidly mounted upon the shaft III and is provided with notches I22 When the gear H0 is out of engagement with gear I09 and the prongs H9 and I are in the notches I22 of the disk I2I, the shaft I8 may be turned in either direction by correspondingly turning the crank 50 in either direction.

The ratchet and pawl mechanism which alternately connects the gears I 03 and I04 to the shaft I02 for driving the negative electrode shaft I8 may be described by reference to Figs. 2, 3,

i and 4. Referring to Fig. 2, the gears I03 and I04 are respectively coaxially connected to ratchet wheels I25 and I26, and may be connected to rotate with the shaft I02, respectively, by pawls I21 and I28 carried by a member I29 rigidly mounted on the shaft I02 between the ratchet wheels I25 and I26. The pawls are respectively provided with a forward, or nose element I30-I3I and a back end, or tail, element I32I33 (see also Fig. 4), and are pivotally mounted upon shafts I34 and I35, respectively. The nose and tail elements of each pawl are spaced transversely of each other so that, as the pawls are moved by the shaft I02 in a circular path, their respective nose or tail elements may be respectively engaged by transversely movable rollers I36 and I31 mounted respectively upon arms I38 and I39 of a pivoted bifurcated relay member I40. This relay member is mounted upon a pivot pin MI and is counter balanced by a weight I42 mounted upon an arm I43. It is moved through a limited arc, so as to move the rollers I36 and I31 transversely with respect to the motion of the pawls I21 and I28, by an armature I44 operable between field poles I45 and I46, these poles being excited by a relay coil I41 wound upon a core member I48 connected between the field poles. The movement of the armature I44 is responsive to the excitation of the field poles I45 and I46 which tend to move the armature counter-clockwise against the tension of springs I49 and I50, the springs being adjustable and the excitation of the field poles being proportional to the current flowing in the coil I41.

In operation, the coil I41 may be connected to carry current responsive to the potential across the arc, or responsive to the current fiowing through the arc, and thereby move the armature I44 relatively to the poles I45 and I46. In the illustrated example, relay coil I41 is designed to carry the full arc current. In normal position, the rollers are positioned opposite to the tail sections I32 and I33. The pawls are, in this position, forced out of engagement with the ratchet wheels. The armature I44 is held in this position by the balanced pull of the field poles and the springs I49 and I50. A slight transverse movement in either direction, however, will bring a roller into engagement with the nose section of a pawl to effect an engagement of the pawl with the ratchet wheel. If the current increases in the coil I41, for example, the field will overcome the pull of the springs I49, I50 and the armature I44 will rotate counterclockwise to carry roller I 36 into the plane of movement of the nose member I 30 of the pawl I21. When the nose member is moved past the roller I36 the nose member is forced forward to move the pawl about its pivot to engage the pawl with the ratchet wheel I25 as illustrated in Fig. 3. In this manner, the shaft I02 drives gear I03, and thereby drives the shaft I8 to move the negative electrode axially. This specific engagement of the pawl and ratchet holds until the roller returns to its position opposite the tail member I32. The pawls are so arranged that the nose is normally opposite to the roller prior to the tail member in each revolution. Therefore, if the pawl nose is moved into engagement with the ratchet wheel, and a slight correction of the electrode will restore normal arc current, the roller will be returned to normal position, and thereby will disengage, or release, the pawl from its ratchet wheel in a fraction of a revolution of the ratchet wheel. If this slight movement of the gear I03 is not sufficient to retract the electrode to a position at which the arc current is normal, the gear I03 will continue to rotate with the shaft I02 until such normal condition is reached. The armature will then move the rollers to the intermediate position, and roller I36 will engage the tail I32 to raise the nose I30 out of its notch on the ratchet wheel to release the gear I03 and thereby stop the axial movement of the electrode.

If the arc current is too low, the pull of springs I49I50 will overcome the pull of the field magnet to move the rollers clockwise. In that case, roller I31 will be moved into position to engage nose I3I of the pawl I28 and will cause it to engage ratchet wheel I26 to move the shaft I06 counter-clockwise and thereby advance the negative electrode I0. If the advance of the electrode is sufficient, within the fraction of the revolution between the nose I3I and the tail I33, the field will move the roller back to normal position and roller I31 will engage the tail I33 to release the gear I04 and thereby again stop the electrode feed mechanism. If the correction required is greater, then the gear I04 will continue to drive the shaft I02 for one or more revolutions until such correction is made.

The roller carrying relay arm which initiates and stops the feed mechanism through operation of the pawls is free to move about its axis on pivot pin I4I, responsive to the pull of armature I40 and of the springs I49--I50. The energy required to engage and disengage the pawls is provided by the prime mover motor 53 above, and there is, therefore, no mechanical load placed on the relay to reduce its sensitivity. The width of the rollers I36 and I31 and their respective positions relatively to the pawls are chosen to give a desired sensitivity.

The pawls are provided with an interlock device which permits only one pawl at a time to move into driving engagement. This is illustrated clearly in Fig. 4. This interlock consists of an interlock bar I5I loosely mounted in the member I29 and projecting outwardly to engage bars I52 and I53 projecting from the pawls I21 and I28, respectively. The length of the bar I5I is such that the movement of one pawl into engagement with its ratchet wheel forces the other pawl out of engagement with its ratchet wheel.

The pawls I21 and I28 are further moved into and out of operation with a snap action. This is imparted by an over-center device. The pawl I2! is pivoted upon shaft I34 by a sleeve I54. The pawl is attached to one end of the sleeve and a cam I is attached to the other end of this sleeve. The cam I55 is provided with an end surface having a high point at its center. A ball I56 urged forward by a spring I51 engages the end surface of the cam and urges the cam and pawl to an end position on either side of this high point in the end surface. The pawl I28 is similarly mounted on a sleeve I58, the pawl being attached to one end of this sleeve and a cam I59 being attached to the other end. The cam I59 is urged to either of its end positions by a ball I60 urged forward by a spring I6I. The springs I51 and NH are suitably mounted in the block I29.

The gears I03 and I 04 are connected to the ratchet wheels I25I26 through resilient connections so as to reduce the shock produced when a pawl engages the rapidly moving ratchet wheel. In Fig. 3, the gear I04, together with its hub and ratchet wheel I26 is illustrated in section. The ratchet wheel I26 is directly attached to a hub member I62. The gear I04 is slidably mounted on the hub I62 between a flange I63 and a disk I64 attached to the end of the hub. A spiral spring I65 is wound about the gear hub. It is attached at one end to a pin I66 in the disk I64 and at the other end it is attached to a pin I61 on the gear I04. Normally the spring which holds the gear I04 at one end of its range of movement is determined by a pin I68 in the gear I 04 projecting into a slot I69 in the flange I63 on the hub I62. When the pawl I28 engages the ratchet wheel I26, the hub I62 is suddenly moved ahead of the gear and an additional tension is placed upon the spring I65. The gear follows the pawl due to the tension on the spring and moves back to its initial position without noticeable shock to the mechanism.

Fig. 4 is a full side view of the block I29 with the pawls I21 and I28. The pawl I2! is pivoted, with its sleeve I54, on the shaft I34 which is mounted in an ear I10 projecting from one corner of the rectangular block I29. cam I55 is mounted on the sleeve I54 and cooperates with the ball I56 to hold the pawl I21 in one or the other of its two positions. The ball I56 is pressed outwardly by the spring I51 to present part of its face to the end of the cam I55. The cam surface has two flat faces at an angle to each other with a high point between them. On either side of this high point, the cam is moved to the extreme position of the pawl. A similar cam I59 is connected to the pawl I 28 by the sleeve I60. The shaft I35 for this pawl is mounted in an ear I'II projecting from an opposite corner of the block I29. This pawl is similarly held in one or the other of its. two positions by a ball I60 urged forward by a spring I6I against the end surfaces of the cam I59.

What I claim as new and desire to secure by Letters Patent in the United States is:

1. In an arc lamp mechanism the combination of a drive shaft, an electrode feeding mechanism, a pawl mechanism attached to said drive shaft to rotate therewith, a ratchet wheel loosely mounted upon said shaft and connected to said electrode feeding mechanism, a pawl actuating relay member pivotally mounted to move transversely of The positioning said rotating pawl in response to variations in an arc condition, and means upon said pawl cooperating with said relay arm to effect a movement of said pawl into and out of engagement with said ratchet wheel responsive to the positioning of said pawl actuating relay member.

2. In an arc lamp mechanism the combination of a drive shaft, an electrode feeding mechanism, a pawl mounted upon said shaft for movement therewith and provided with an engaging element and a releasing element spaced transversely of each other, a ratchet wheel loosely mounted on said shaft and connected to said electrode feeding mechanism, a relay member operable transversely of said pawl in response to variations in an arc condition, and in cooperating relationship with said engaging and releasing elements on said pawl to effect operation of said feeding mechanism,

3. In an arc lamp, the combination of a pair of electrodes, means for moving one of said electrodes relatively to the other of said electrodes to establish an arc therebetween, a relay coil responsive to a condition of said arc, a relay member actuated by said relay coil, a drive shaft, a pawl mechanism rotatable with said drive shaft, a ratchet wheel loosely mounted upon said drive shaft and operable with said drive shaft when engaged by said pawl mechanism to actuate said electrode moving means, and means upon said pawl mechanism cooperating with said relay arm to effect a movement of said pawl into and out of engagement responsive to the position of said relay member.

4. In an arc lamp mechanism the combination of a drive shaft, an electrode feed mechanism, a pawl mounted upon said shaft for movement therewith, a ratchet wheel loosely mounted on said shaft and connected to said electrode feed mechanism, a relay member operable transversely of said pawl in response to variations in an arc condition, and means upon said pawl including an engaging member and a releasing member spaced transversely of each other and cooperating with said relay member to effect engagement and release between said pawl and said ratchet wheel in accordance with the positioning of said relay member in response to said are condition.

5. In an arc lamp, the combination of a pair of electrodes, an actuating mechanism for one of said electrodes comprising feed rolls, a relay coil energized in response to a condition of the are between said electrodes, a relay member provided with a pair of actuating members pivotally mounted and rotatable responsive to the energization of said relayooiLa drive shaft, a pair of pawls mounted upon said shaft to rotate with said drive shaft, a pair of ratchet wheels loosely mounted upon said drive shaft and operable when engaged by said pawls respectively to rotate with said shaft, means upon said pawls cooperating with said relay member to engage or release said ratchet wheels in response to the positioning of said relay member, and means between said ratchet wheels and said electrode feed rolls to drive said rolls in either of two opposite directions.

6. In an arc lamp mechanism the combination of a pair of electrodes, an actuating mechanism for one of said electrodes, a relay coil energized in response to a condition of the are between said electrodes, a relay member provided with a pair of actuating members pivotally mounted and rotatable responsive to the energizationof saidrelay coil, a drive shaft. a pair of pawls mounted upon said drive shaft to rotate with said drive shaft, a pair of ratchet wheels loosely mounted upon said drive shaft and connected to said feed mechanism, one of said ratchet wheels being connected to advance said electrode and the other of said wheels being connected to retract said electrode, means upon said pawls respectively cooperating with said actuating members to effect an engagement or a release of said ratchet wheel in response to the positioning of said actuating member transversely of said pawl, and interlocking means between said pawls to permit an engagement between only one of said ratchet wheels and one pawl at a time.

7. In an arc lamp electrode feeding mechanism the combination of electrode feed rolls, a drive shaft, a pawl'mechanism attached to said drive shaft to rotate therewith, a ratchet wheel and gear loosely mounted on said drive shaft and CLARENCE T. CROCKER. 

